Variable speed drive



July 29, 1969 AsHToN ETAL 1 3,457,797

VARIABLE SPEED DRIVE 7 Filed Oct. 12, 1967 2 Sheets-Sheet 1 mvrjw'nims.ROBERT ASHTON W/A B507 0. Wt'BER WAL TEA H/RS CH gW-JQL ms ukuliATTORNEYS.

July 29, 1969 v ASHTON ETAL 3,457,797

VARIABLE SPEED DRIVE Filed Oct. 12, 1967 2 Sheets-Sheet 2 A TTORNEKS.

United States Patent 3,457,797 VARIABLE SPEED DRIVE Robert Ashton,Islington, Ontario, Wilbert D. Weber,

Nashville, Ontario, and Walter Hirsch, Don Mills, Ontario, Canada,assignors to Massey-Ferguson Industries Limited, Toronto, Ontario,Canada Filed Oct. 12, 1967, Ser. No. 674,885 Int. Cl. F16h 55/44, 7/10US. Cl. 74230.17 Claims ABSTRACT OF THE DISCLOSURE A variable speeddrive including a variable speed double pulley assembly with a pair ofpulleys having variable, inversely proportional diameters respectivelyconnected by belts to spaced input and output pulleys. The variablespeed pulley assembly is slideably mounted on a carrier member which ismovable in opposite directions with respect to the input and outputpulleys to vary the speed of the output pulley. A belt tensioning deviceis mounted on the carrier member for exerting tension on the beltsthrough exertion of a constant force on the variable speed pulleyassembly in all positions of the carrier member.

This invention relates generally to transmissions and is particularlyconcerned with variable speed belt drives.

It is conventional to transmit drive from an input pulley to the outputpulley through a variable speed double pulley assembly having inverselyproportional diameters such that by moving the variable speed pulleyassembly relative to the input and output pulleys, the drive ratiobetween the input and output pulley is adjusted. In such arrangements,it is frequently a problem to maintain the proper belt tension duringmovement of the variable speed pulley assembly and after its positionhas been adjusted.

It is an object of this invention therefore to provide a variable speedbelt drive wherein the speed ratio and proper belt tension can beaccurately controlled throughout the operating range of the drive.

Another object is to provide a variable speed belt drive having amovable variable speed drive unit including a pair of variable pulleyshaving inversely proportional diameters in which tension is maintainedon the belts through application of a constant force to the variablespeed drive unit in all positions thereof with respect to the input andoutput pulleys of the drive.

In accordance with the present invention, a variable speed drive unithaving a pair of pulleys of inversely proportional variable diameters isslideably mounted on a carrier member which in turn is movably mountedon a supporting frame. Spaced input and output pulleys are respectivelyconnected by belts with the variable speed pulleys so that movement inopposite directions by the variable speed drive unit on the carriermember varies the speed on the output pulley with respect to the inputpulley. Proper tension is maintained on the belts by a belt tensioningdevice mounted on the carrier and connected with the variable speeddrive unit to maintain a constant force on the variable speed drive unitin all positions of the carrier member.

Other objects, advantages and features of the invention will becomeapparent from the following description taken in connection with theaccompanying drawing in which:

FIG. 1 is an elevational view of a variable speed belt drive embodyingthe invention;

FIG. 2 is a sectional view taken along lines 22 of FIG. 1; and

FIG. 3 is a view similar to FIG. 2 illustrating a modified from of theinvention.

In FIG. 1, reference numeral 2 designates a supporting frame or body ofa self-propelled vehicle such as an Patented July 29, 1969 agriculturalcombine. Fixed to the end of an input shaft 4 15 an input pulley 6, andan output pulley 10 is fixed to the end of an output shaft 8. Pulleys 6and 8 are drivingly connected together by belts 12 and 14 extendingrespectively from pulleys 6 and 8 to a variable speed drive unitdesignated collectively by reference numeral 16.

The variable speed drive unit 16 is mounted on a carrier member 18 whichin turn is movably mounted on the supporting frame 2 and includes a pairof spaced, parallel arms 20 and 22 each formed with an elongated slot24. Arms 20 and 22 of the carrier member '18 are secured together at oneend by a bracket 26 having a depending flange 27 and an upstandingflange 28. A pair of spaced, apertured lugs 29 are formed on thedepending flange 27 for supporting a tubular sleeve 32 extendingtransversely between the arms 20 and 22. Rearwardly projecting cars 30are formed intermediate the ends of the upstanding flange 28. Sleeve 32rotatably receives a shaft 34 which is mounted in a bearing member 36supported in frame 2. The opposite end of shaft 34 is secured to a postor upright frame member 40 by a conventional fastener 38. Consequently,the carrier member 18 is pivotally supported on the supporting frame 2for rotation about the axis of shaft 34.

The variable speed drive unit 16 includes a yoke member 42 with spaced,parallel arms 44 and 46 between which is supported the shaft 48 of adouble pulley assembly 50. Rollers 51 are mounted on shaft 48 forengagement with slots 24 in the arms of carrier member 18 such that thedouble pulley assembly and yoke are slideably supported on carriermember 18 for movement along the length of arms 20 and 22. The doublepulley assembly 50 includes a pair of fixed sheaves 52 and 54 betweenwhich is mounted a movable sheave 56. The movable sheave 56 cooperateswith the fixed sheaves 52 and 54 to define a pair of pulleys 55 and 57having variable, inversely proportional diameters for engagementrespectively with belts 14 and 12 as shown in FIG. 2. Movement of sheave56 toward sheave 54 increases the effective diameter of pulley 55 onwhich belt 14 is mounted and correspondingly decreases the effectivediameter of pulley 57 on which belt 12 is mounted.

Mounted between the base portion of yoke 42 and the upstanding flange 28of bracket 26 is a hydraulic ram 58. The cylinder 60 of ram 58 ispivotally connected by a pin 62 to a bracket 64 mounted on the basemember of yoke 42. The piston 66 of ram 58 is pivotally connected by pin68 to the lugs 40. Cylinder 60 is connected with a source of constantpressure and fluid pressure within cylinder '60 tends to extend piston66 from the cylinder and bias the double pulley assembly 50 and yoke 42toward the left as viewed in FIG. 2. Consequently, by maintaining aconstant fluid pressure in the cylinder of ram 58 tending to extend theram, tension on belts 12 and 14 is maintained by applying a constantforce to the double pulley assembly 50. A relief valve may be providedin the hydraulic system to limit the pressure in cylinder 60 and preventoverload of the ram and belts.

In the illustrated embodiment, carrier member 18 is moved about the axisof shaft 34 by a hydraulic ram 70 having its cylinder 72 pivotallymounted at 74 on frame 2, and its piston 76 pivotally connected by a pin78 to an actuating arm 80 in the form of a channel section (FIG. 2).Extension of ram 70 causes carrier member 18 to move in a clockwisedirection to decrease the distance between the double pulley assembly 50and the input pulley 6 to thereby cause the movable sheave 56 to movetoward the fixed sheave 52 and increase the diameter of the variablepulley portion 57. As the carrier member moves about the axis of shaft34, the ram 58 maintains proper tension on belts 12 and 14 by permittingthe double pulley assembly and yoke 42 to move along slots 24 as thecarrier member changes position.

FIG. 3 illustrates a modified arrangement of the invention wherein aspring assembly is utilized in place of the hydraulic ram 58. A springseat plate 82 is carried by one end of a threaded rod 84 mounted in across member 85 secured between the ends of the parallel arms of acarrier member 87 which corresponds to carrier member 18 in the 'FIG. 2embodiment. Lock nuts 86 maintain the threaded rod 84 in its adjustedposition with respect to the frame portion 85. The spring support plate82 is apertured adjacent its ends to receive rods 88 which aretelescopically received in cylinders 90 seated against the base portionof yoke 42. Coil springs 92 are seated between spring seat member 82 andthe base portion of yoke member 42 and surround the rods and cylinders88, 90 to urge yoke 42 toward the left and maintain substantially propertension on belts 12 and 14.

While specific embodiments of the invention have been illustrated anddescribed in the foregoing specification, it will be apparent to thoseskilled in the art that the invention is not limited to the exactconstruction shown, but that various alterations and modifications canbe made without departing from the scope and spirit of the invention.

We claim:

1. A variable speed drive comprising a supporting frame; a carriermember movably mounted on the supporting frame; a variable speed driveunit slideably mounted on the carrier member, said variable speed driveunit comprising a pair of pulleys having variable, inverselyproportional diameters; an input pulley and an output pulley spacedapart a fixed distance from each other; a first belt connecting theinput pulley with one of said pair of pulleys and a second beltconnecting the output pulley with the other of said pair of pulleys sothat rotation of said input pulley is transmitted to said output pulleythrough said variable speed drive unit; said input and output pulleysbeing arranged with respect to said carrier member such that movement ofthe carrier member in one direction increases the distance between thevariable speed pulley and the input pulley to thereby decrease thediameter of said one pulley of said pair and proportionally increase thediameter of said other pulley of said pair, and movement of the carriermember in the opposite direction increases the distance between thevariable speed pulley and said output pulley to thereby decrease thediameter of said other pulley of said pair and proportionally increasethe diameter of said one pulley of said pair; and belt tensioning meansmounted between said carrier member and said variable speed drive unitfor applying a continuous force on said variable speed drive unit totension the belts in all positions of the carrier member by permittingthe variable speed drive unit to slide along the carrier member as thecarrier member changes position.

2. A variable speed drive as claimed in claim 1 wherein said belttensioning means comprises an expansible and contractible constantpressure hydraulic ram having one end mounted on the carrier member andits other end connected with the variable speed drive unit, said ramthereby exerting a constant force on said variable speed drive unit.

3. A variable speed drive as claimed in claim 1 wherein said carriermember includes a pair of spaced, parallel arms each having an elongatedslot, and wherein said variable speed drive unit is mounted in saidslots.

4. A variable speed drive as claimed in claim 3 wherein said variablespeed drive unit further comprises a U- shaped yoke member having a pairof spaced, parallel arms joined by a base portion with said pair ofpulleys being received between the yoke arms and having a shaft mountedon said arms, and rollers on the ends of said shaft engaged with theslots in the arms of the carrier member.

5. A variable speed drive as claimed in claim 4 further including 'meanssecuring the arms of the carrier member together adjacent their ends,and wherein said belt tensioning means is mounted between said securingmeans and the base portion of the yoke member.

6. A variable speed drive as claimed in claim 5 wherein said securingmeans comprises a bracket having an upstanding flange formed with a pairof apertured ears; and wherein said belt tensioning means comprises ahydraulic ram the piston of which is connected with said ears and thecylinder of which is connected with the base portion of said yokemember, such that fluid pressure within the cylinder tends to cause thepiston to extend from the cylinder and move the variable speed driveunit along the slots in the carrier arms away from said bracket andapply tension to said belts, said cylinder being connected with a sourceof constant pressure whereby the piston will retract into the cylinderto permit the variable speed drive unit to move toward the bracket toprevent the constant force from being exceeded and will extend from thecylinder to prevent a decrease in the force.

7. A variable speed drive as claimed in claim 6 wherein said bracketincludes a depending flange having a pair of forwardly projecting lugs;and further including a sleeve member supported by said lugs andextending transversely of said carrier arms; a shaft rotatably receivedwithin said sleeve, said shaft having one end mounted on the supportingframe whereby the carrier member is pivotally mounted on said supportingframe and moves about the axis of said shaft to vary the drive betweenthe input and output pulleys.

8. A variable speed drive as claimed in claim 5 wherein said securingmeans comprises a cross member extending between the ends of the carrierarms; and wherein said belt tensioning means comprises a spring assemblymounted between said cross member and the base portion of said yokemember, for biasing the variable speed drive unit in a direction toapply tension to said belts, and means for adjusting the biasingforce ofsaid spring assembly.

9. A variable speed drive as claimed in claim 8 wherein said adjustingmeans comprises a threaded rod adjustably mounted in said cross member;and wherein said spring assembly comprises a spring support platecarried by said threaded rod; a pair of cylinders seated at one endagainst the base portion of said yoke member, a pair of guide rodsmounted on the spring support plate and each telescopically received inone of said cylinders, and a coil spring surrounding each of thecylinders with its ends mounted between the base portion of the yokemember and said I spring support plate.

10. A variable speed drive as claimed in claim 1 wherein said belttensioning means comprises spring means mounted between the carriermember and variable speed drive unit.

References Cited UNITED STATES PATENTS FRED C. MATIERN, 111., PrimaryExaminer JAMES A. WONG, Assistant Examiner US. Cl. X.R. 4 242-14, 242.15

